Baffle type heat treating furnace



April 9, 1957 Filed Oct. 19, 1953 H. N. IPSEN BAFFLE TYPE HEAT TREATING FURNACE 2 Sheets-Sheet 1 April 9, 1957 H. N. lPsEN BAFFLE TYPE HEAT TREATING FuRNAcE Filed om.v 19. 1953 2 Sheets-Sheet 2 cH 11er-:NEM

BAFFLE TYPE HEAT TREATING FURNACE Harold N. Ipsen, Rockford, lli. Application October 19, 1953, Serial No. 386,335

Claims. (Cl. 263-46) This invention relates to heat treating furnaces and, more particularly, to a furnace in which a baille composed of a hearth, side walls and an arch is disposed within the furnace chamber and receives the workpieces during treating. A fan circulates the heated atmosphere within the chamber while the baille serves to cause a more even distribution of heat.

The general object of the invention is to provide a heat treating furnace with a new and improved baille which may be assembled and disassembled within the furnace chamber Without dismantling the furnace, which is assembled and held in place without the use of mortar or the like, and which extends the full length of the chamber.

A more detailed object is to construct the baille in sections which are insertible through the door of the furnace and which are held together by novel lap joints permitting the baille to be assembled completely inside the chamber with the ends of the baille abutting against the end walls of the furnace.

Another object is to correlate in a novel manner the size of the fan with the size of a hole in the arch of the baffle to permit the fan to be inserted through this hole while minimizing the size of the hole.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure l is a fragmentary side elevation of a heat treating furnace embodying the novel features of the present invention, parts being broken away and shown in section.

Fig. 2 is a perspective view of the baille.

Figs. 3 and 4 are enlarged fragmentary sectional views taken respectively along the lines 3--3 and 4-4 in Fig. 2. F Fin 5 is a sectional view taken along the line 5--5 in Fig. 6 is a fragmentary perspective View of the baille with parts broken away.

Fig. 7 is a fragmentary longitudinal sectional view of the end or lip portion of the baille hearth.

As shown in the drawings for purposes of illustration, the invention is embodied in a heat treating furnace 1t) in which worltpieces to be treated are heated in a charnber 11 defined by the top wall 12, the bottom Wall 13, the end Walls 14 and 15 and side walls 16 of the furnace. The furnace chamber is heated by conventional heating elements such as the electric heating tubes 17 spanning the side walls 16 and extending across the iloor 13 of the furnace. To prevent the workpieces from oxidizing during treatment, an inert atmosphere composed primarily of hydrogen and nitrogen is admitted through a pipe 18 extending through the top wall 12 and this atmosphere is circulated across the heating elements 17 and the workpieces by a fan 19. Herein, the latter comprises four rectangular blades 20 projecting radially from and equally spaced around a vertical shaft 21 which projects down into the chamber 11 through the top wall 12 and is driven by a suitable motor (not shown).

twbatented Apr. 9, 1957 Within the chamber 11 is a baille 22 which surrounds the workpieces and causes the heated atmosphere to be circulated more evenly to prevent the occurrence of hot spots. The baille is made of a ceramic refractory material and includes a tlat horizontal hearth 23 disposed above the furnace iloor 13 over the heating elements 17 and supported by blocks 24 resting on the oor. Upstanding from the side edges of the hearth 23 and spaced from the side walls 16 of the furnace are the side walls 25 of the baille and these walls extend the complete length of the chamber with their ends abutting against the end walls 14 and 15 of the furnace as shown in Fig. l. A cover or arch 26 for the baille spans the side walls of the latter and is formed with a central hole 27 above the fan shaft 21. With this arrangement, the inert gas within the chamber 11 is circulated by the fan down across the heating tubes 17, up into the baflle through holes 28 in the hearth 23 and up through the hole 27 to fan.

Workpieces are introduced into the furnace chamber 11 through an opening 29 in the end wall 14, this opening being closed by a suitable door 30. After the heat treating is completed, the workpieces are removed through a second door-controlled opening 31 in the rear end wall 15. If desired, such removal may be eected by an endless chain 32 which passes beneath the bottom wall 13 and then up across the hearth 23. A lug or dog (not shown) carried by the chain engages the workpieces and slides them along the hearth and onto a receiving platform 33 adjacent the exit opening 31.

l'n order that the baille 22 may be assembled and disassembled easily within the chamber 11 without dismantling the furnace 10 and still extend the full length of the chamber, the present invention contemplates the provision of a baille which is composed of sections insertible through the opening 29 and capable of being fit and held together without the use of mortar or the like. These sections merely abut against each other and, by a novel construction of certain edges of these sections, the latter interlock and support each other so that the baille is a rigid assembly. Such interlocking is permitted even though adjacent sections abut ilrmly against each other and the end sections abut against the end walls 14 and 15 of the furnace.

As shown in Fig. 2 of the drawings, each side wall 25 of the baille 22 is formed by three flat rectangular sections 34, 35, and 36 which are disposed vertically and rest on the marginal portions of the hearth 23. In each wall, the edges of the intermediate section 35 overlap the adjacent edges of the end sections 34 and 36 on the inside thereof and thus the intermediate section is prevented from shifting outwardly. Spanning Vthe two opposed end sections 34 of the baille side walls is a curved arch section 37 which rests on and interlocks with the upper rends of Wall sections while a second arch section 38 similarly spans and interlocks with the end Wall sections 36. The central portion of the arch is formed by two partial arch sections 39 each resting on the upper end of one of the intermediate wall sections 35 and interlocked with the latter. The edges of each partial arch section 39 overlap the adjacent margins of the arch sections 37 and 38 so that the partial sections are supported by the full arch sections as well as by the baille walls and also are prevented from moving inwardly. With the overlapping joints, the intermediate wall sections 35 and the partial arch sections may be moved into place and tit closely with the end wall and arch sections 34, 36, and 37, 38 already 'in place and abutting against the ends of the furnace. At the same time, both the intermediate sections and the partial arch sections are held rmly against shifting since neither intermediate section can move outwardly while neither partial arch section can move inwardly and the two are interlocked together.

.ln the present instance, the hearth 23 is formed by a plurality of ceramic plates di) disposed end to end and resting on the blocks 2d. Adjacent plates are interlocked by tongue and groove jointsdl which prevent the plates from shifting relative to each other. At the front of the forwardmost plate is a ceramic section 42 of quarter circle cross section to extend forwardly and downwardly from the front of the hearth. As shown in Fig. 7, this section is connected to the front hearth plate by atongue` and groove joint 43 and thus constitutes the lip of the hearth.

Along side edges of the hearth plates 4S in the upper surfaces thereof are upwardly opening grooves Lili (Fig. 6) extending the` full length of furnace chamber il. and receivingA tongues 45 projecting downwardly from the lower edges of the baille wallsections 34, 35` and 36. The forward edges of the sectionsl'and the-rear edges of the sections 36 are flat so that these edges may abut respectively against the front and rear end walls lid and l of the furnace as shown in Fig. l. At their inner edges, these end sections of the baffle walls are formed withflanges 46 extending throughout the vertical length of the sections and projecting from the outer half of the sections, these flanges being half as thick as the Wall sections. Along the vertical edges of the intermediate wall sections 35 are complementary flanges 47 (Fig. 4) projecting from the inner half of these sections. As illustrated in Fig. 4, the flanges 47 overlap the flanges 46 on the inside thereof and thus form the joints between the wall sections while at the same time providing the baille walls 25 with a smooth and continuous surface.

Projecting from the ends of each of the full arch sections 37 and 3S are tongues 48 (Fig. 6) which are received in mating grooves 49 in the upper edges of the wall sections 34 and 36. A similar tongue and groove 50, 51 (Fig. 5) joins each partial arch section 39 to the corresponding intermediate wall section 35 and forms the interlocking connection between the two. Along the opposing edges of the arch sections 37 and 38 are flanges 52 (Figs. 3 and 6) projecting from the inner halves of the sections and in under complementary flanges 53` (Figs. 3 and 5) extending along the outer half of theedges of the partial arch sections. Thus, the latter sections are supported by the arch sections 37 and 3f? through the medium of the flanges 52 and 53 and, as illustrated in Fig. 3, these flanges constitute-lap joints which, like the joints between the wall sections, present a smooth and continuous surface.

Herein, the partial arch sections 39, stopshort of each other so that their upper edges are, spaced apart and cooperate with the inner edges of the arch sections 37 and 38 to define the hole 27. Preferably, the size and shape of this hole is correlated in a novel manner with the size and construction of the fan i9 topermit the latter to be inserted up through the hole during assembly of the fan while minimizing the size of the hole. For this purpose, the hole is made polygonal in shape such as the square hole shown in Fig. 2 and the blades 2li are angularly spaced around the shaft 2l so that, when the fan is properly disposed below the hole, each blade projects towards one vertex of the hole. In the illustrated form of the invention, for example, there are four blades 20 equally spaced around the fan shaft and the combined length of two alined blades is slightly less than the length of a diagonal of the square hole. Thus, when the blades are disposed along the diagonals of the holes as shown in phantom in Fig. 2, the fan just lits through the hole. ln this way, the hole is kept as small as possible while still permitting the fan to be inserted through the hole without dismantling the baffle 22.

To assembleV the baffle 22, thehearth plates 40 first areplacedon the blocks 24 and the lip 42'is attached to the front plate. Next the end wall sections 34 and 36 are set in place with their tongues 45 in the grooves i4 and their outer edges abutting against the end walls 14 and 15 of the furnace. Then the intermediate wall sections 35 are positioned. This is done by placing each intermediate section opposite the space between the two end sections 3d and 36 and inside the baille as shown in broken lines in Fig. 5 and then moving the section out until the flanges 47 abut against the flanges d6 and the tongue d5 drops into the groove 44. With the side walls 25 of the baille assembled, the arch 26 is put together by first placing the full arch sections 37 and 38 on the end sections 34 and 36 respectively with the tongues 48 received in the grooves 49. Finally, the two partial arch sections 39 are located by tilting each section so that it passes through the space between the full arch sections 37 and 38 and then turning the section to the position shown in broken lines in Fig. 5. With the partial arch section in this position, it is moved into place with the flanges 53 resting on thel flanges 52 and the tongue 5t) projecting into the groove 5l. In effect, the end wall sections 34 and the arch section 37 form one unit while the other end wall and arch sections 36 and 33 form Aanother unit and these two units are held together by the intermediate wall sections and the partial arch sections 39. In turn, the intermediate and partial arch sections are held firmly in place by the cooperation of the flanges 46, 47, 52and 53 and the tongue and groove joint Sti, 51.

It will be observed that the baffle 22 is readilyV assembled within the furnace chamber without dismantling the furnace. Each ofthe various sections forming the baille is small enough to be inserted in the furnace opening 29 and the sections may be-pieced together within the confines of the chamber and are held together without mortar. Thefnovel joints between the sections formed by the overlapping flanges 46, 47 and 52, 53 permit'the end wall sections 34-and 36 and arch sections 37 and 38 to be set in place before the intermediate wall sections 35 and the partial arch sections 39 so that the end wall and arch sections may be in abutting engagement with the end walls 14 and 15 of the furnace. By dividing the central portion of the arch into the two sections 3g, each is small enough to pass between the arch sections 37 and 38 and be finally moved into place from the outside of the baille.

I claim as my invention:

l. A heat treating furnace having, in combination, a walled enclosure defining a chamber and having an opening in one end wall thereof and a baille disposed within said chamber and comprising a hearth supported by said enclosure and disposed above the tloor of the furnace, a first wall member disposed along one side of said chamber and abutting against one end wall of said enclosure, a second side wall member abutting against the other end wall of said enclosure and alined with but spaced from said first member, an intermediate wall member disposed between said first and second wall members and having side flanges overlapping said first and secondmembers on the inside and alongthe margins thereof, three similar side wall members disposed along the other side of said chamber, a first arch spanning and resting on the opposing sidewall members at one end of said chamber, a second arch spanning and resting on the opposing sidewall members at the other end of said chamber, and two partial arches, one resting on each of said intermediate wall members and each having side flanges overlapping the margins of said arches on the outside thereof.

2. In .a heat treating furnace, the combination of,I a walled enclosure defining a `chamber and a baille disposed within said chamber and comprising a hearth supported fby said enclosure and disposed above the floor of said chamber, a set of alined side wall members resting on said 'hearth in an edge to edge relation and including a first intermediate wall member, a similar set of side wall members paralleling but spaced from said first set and including a second intermediate wall member opposing said rst intermediate Wall member, arch sections resting on each of said intermediate wall members, and arch members ydisposed on opposite sides of said arch sections and spanning said `sets of wall members, said arch members having portions projecting laterally from the lower part of the :edges thereof and in under said arch sections to support said arch sections with the upper part of said edges being disposed entirely to the side of the arch sections to permit removal of the arch sections by upward movement.

3. A heat treating furnace having, in combination, a walled enclosure defining la chamber, a baille `disposed within said chamber and comprising a hearth supported by said `enclosure and `disposed above the floor of said chamber, a rst baffle end unit abutting against one of said walls of said enclosure and including opposed wall portions resting on said hearth and an `arch portion spanning said wall portions, a second and similar bafle end unit spaced from said rst unit and abutting `against the opposite wall of said enclosure with each wall portion alined with -a wall portion of said rst unit, an intermediate wall member disposed between `one pair of alined wall portions and having side flanges Ioverlapping the margins of said `alined portions along the inside thereof, a second intermediate wall member ldisposed between and similarly overlapping the other pair of alined wall portions, and two partial `arch members, one

resting on each of said intermediate wall portions and each having side flanges overlapping and resting on the margins of said `arch portions along the outside thereof, the upper ends of said arch members being spaced apart to define an opening, ra shaft projecting down from the upper wall of said enclosure and disposed coaxially with said opening, and a fan mounted on said shaft above said opening.

4. A heat treating furnace as dened in claim l in which said walled enclosure denes a space above said barile to permit said partial arches to be removed without dismantling the enclosure.

5. A heat treating Ifurnace as defined by claim 2 in which said walled enclosure defines a space above said bafe to permit said arch sections to rbe removed without dismantling the enclosure.

References Cited in the file of this patent UNITED STATES PATE-NTS 798,524 McNab Aug. 29, 1905 919,200 Menton `et al Apr. 20, 1909 1,607,681 Manion Nov. 23, 1926 1,710,870 Forse Apr. 30, 1929 2,075,694 Benner Mar. 30, 1937 2,192,752 Miller Mar. 5, 1940 2,611,790 Koch Sept. 23, 1952 

